diff --git a/src/mesa/main/glformats.c b/src/mesa/main/glformats.c
index 66b29ed..2525993 100644
--- a/src/mesa/main/glformats.c
+++ b/src/mesa/main/glformats.c
@@ -1886,6 +1886,7 @@
       case GL_RED:
          if (_mesa_has_rg_textures(ctx))
             return GL_NO_ERROR;
+         /* fallthrough */
       default:
          return GL_INVALID_OPERATION;
       }
@@ -2927,6 +2928,7 @@
          case GL_RGBA:
             if (_mesa_has_OES_texture_float(ctx) && internalFormat == format)
                break;
+         /* fallthrough */
          default:
             return GL_INVALID_OPERATION;
          }
@@ -2935,6 +2937,7 @@
       case GL_HALF_FLOAT_OES:
          if (_mesa_has_OES_texture_half_float(ctx) && internalFormat == format)
             break;
+         /* fallthrough */
       default:
          return GL_INVALID_OPERATION;
       }